Traditional methods for closing tissue wounds or incisions include the use of glues, sutures, clips, or staples. While such techniques are generally adequate in sealing tissue wounds or incisions, they have associated problems that limit their use. For example, often lead to scar formation, infection, and a multitude of immunological responses. Tissue incompatibility with sutures, clips, or staples may cause fistulas, granulomas, and neuromas that can be painful and difficult to treat. Sutures, clips, or staples may also tend to cut through weak parenchymatous or poorly vascularized tissue. Additionally, sutures leave behind a tract that can allow for leakage of fluids and can provide a convenient entry point for a variety of organisms.
The success of traditional methods in sealing tissue wounds or incisions also is very dependent on the skill of the practitioner performing such methods, especially when microsurgery is being performed.
An alternative to traditional methods for sealing tissue wounds or incisions is the use of compositions suitable for tissue welding. By “tissue welding” it is meant that an energy source is used to excite the composition, which results in the sealing or closure of the tissue wound or incision. Typically, a tissue welding composition will be applied to the area of the tissue that requires sealing. Upon excitation by an energy source, the composition fuses to the tissue, and the bonding between the composition and the tissue allows the severed parts of the tissue to be proximal to each other, much in the same way as when sutures, staples, or clips are used. Such tissue welding compositions are absorbable within a few weeks and, therefore, do not cause tissue scar formation.
Numerous instruments are known which coagulate, seal, join, or cut tissue. Some of these devices may operate with a heating element in contact with the tissue, with an ultrasonic heater that employs frictional heating of the tissue, or with a mono- or bi-polar electrode heating system that passes current through the tissue such that the tissue is heated by virtue of its own electrical resistance.
Some devices heat the tissue to temperatures such that the tissue is either “cut” or “sealed”, as follows. When tissue is heated in excess of 100° Celsius, the tissue will be broken down and is thus, “cut”. However, when the tissue is heated to temperatures between 50° to 90° Celsius, the tissue will instead simply “seal” or “weld” to adjacent tissue. Numerous devices employing the same general principle of controlled application of a combination of heat and pressure can be used to join or “weld” adjacent tissues to produce a junction of tissues or an anastomosis of tubular tissues.
Mono-polar and bipolar probes, forceps or scissors use high frequency electrical current that passes through the tissue to be coagulated. The current passing through the tissue causes the tissue to be heated, resulting in coagulation of tissue proteins. In the mono-polar variety of these instruments, the current leaves the electrode and after passing through the tissue, returns to the generator by means of a “ground plate” which is attached or connected to a distant part of the patient's body. In a bipolar version of such an electro-surgical instrument, the electric current passes between two electrodes with the tissue being placed or held between the two electrodes.
There are many examples of such mono-polar and bipolar instruments commercially available today from companies including Valley Lab, Cabot, Meditron, Wolf, Storz and others worldwide.
In ultrasonic tissue heaters, a very high frequency (ultrasonic) vibrating element or rod is held in contact with the tissue. The rapid vibrations generate heat causing the proteins in the tissue to become coagulated.
Applying electrically generated plasma to medical application is known in the art.
For example, electrosurgery surgery is known in the art and is performed by electrical methods. Its development has been driven by the clinical need to control bleeding during surgical procedures. While heat has been used medically to control bleeding for thousands of years, the use of electricity to produce heat in tissue has only been in general use since the mid 1920's, and in flexible endoscopy since the 1970's. Electrosurgery offers at least one unique advantage over mechanical cutting and thermal application: the ability to cut and coagulate tissue at the same time. This advantage makes it the ideal surgical tool for the gastroenterologist.
Electrosurgical Generators provide the high frequency electrical energy required to perform electrosurgery and some of these are equipped with an option to use argon gas enhanced electrosurgery. Argon gas enhanced or Argon Plasma Coagulation (APC) has been in long use in the operating room setting and is used intermittently, usually for parenchymal organ surgeries.
Argon plasma equipped electrosurgery systems were adapted to be able to be used in flexible endoscopic procedures of the gut and lung.
Optical emission spectroscopy is known in the art and is commonly used to identify chemical composition and abundance of chemical species in mixtures. Plasma may excite the mixture, and the emitted fluorescence is collected and analyzed in a spectrometer.
Large amount of research was devoted to laser tissue welding. Companies such as Laser Tissue Welding Inc. (Texas, USA) have started clinical trials in 2009. This company targets for internal organs closure. Seraffix, an Israeli startup company using a robotic CO2 laser device also started clinical trials in 2009. Laser soldering utilizes IR laser (wavelength>1 um), mostly CO2 source, which activates thermally albumin that is applied pre activation. The laser grater advantage is its spatial accuracy which can get to micrometers resolution. However, for soldering application, the spatial accuracy is of less importance.
The main disadvantage of the laser is that its thermal activation is linearly dependent on the time it “hits” the targeted area; this means that if the laser beam stays too long on the same spot, it burns the albumin and the tissue in vicinity, performs poor adhesion and tissue necrosis.
U.S. Pat. No. 7,033,348; titled “Gelatin based on Power-gel™ as solders for Cr4+ laser tissue welding and sealing of lung air leak and fistulas in organs”; to Alfano, R. et. al; discloses a method of welding tissue, involves joining edges of tissue wound and irradiating wound with laser selected from group consisting of Cr4+ lasers, semiconductor lasers and fiber lasers where the weld strength follows the absorption spectrum of water. The use of gelatin and esterified gelatin as solders in conjunction with laser inducted tissue welding impart much stronger tensile and torque strengths than albumin solders. Selected NIR wavelength from the above lasers can improve welding and avoid thermal injury to tissue when used alone or with gelatin and esterified gelatin solders. These discoveries can be used to enhance laser tissue welding of tissues such as skin, mucous, bone, blood vessel, nerve, brain, liver, pancreas, spleen, kidney, lung, bronchus, respiratory track, urinary tract, gastrointestinal tract, or gynecologic tract and as a sealant for pulmonary air leaks and fistulas such as intestinal, rectal and urinary fistulas.
US application 20060217706; titled “Tissue welding and cutting apparatus and method”; to Lau, Liming, et. al.; discloses a surgical apparatus and methods for severing and welding tissue, in particular blood vessels. The apparatus includes an elongated shaft having a pair of relatively movable jaws at a distal end thereof. A first heating element on one of the jaws is adapted to heat up to a first temperature and form a welded region within the tissue, while a second heating element on one of the jaws is adapted to heat up to a second temperature and sever the tissue within the welded region.
U.S. Pat. No. 7,112,201; titled “Electrosurgical instrument and method of use”; to Truckai, Csaba, et. al.; discloses an electrosurgical medical device and method for creating thermal welds in engaged tissue. In one embodiment, at least one jaw of the instrument defines a tissue engagement plane carrying a conductive-resistive matrix of a conductively-doped non-conductive elastomer. The engagement surface portions thus can be described as a positive temperature coefficient material that has a unique selected decreased electrical conductance at each selected increased temperature thereof over a targeted treatment range. The conductive-resistive matrix can be engineered to bracket a targeted thermal treatment range, for example about 60° C. to 80° C., at which tissue welding can be accomplished. In one mode of operation, the engagement plane will automatically modulate and spatially localize Ohmic heating within the engaged tissue from RF energy application-across micron-scale portions of the engagement surface. In another mode of operation, a conductive-resistive matrix can induce a “wave” of RF energy density to sweep across the tissue to thereby weld tissue.
US application 20030055417; titled “Surgical system for applying ultrasonic energy to tissue”; discloses an ultrasonic surgical instrument for sealing and welding blood tissues, having wave guide moving relative to introducer and ultrasound source coupled to elongated jaws moving to selected approximate position.
U.S. Pat. No. 6,323,037; titled “Composition for tissue welding and method of use”; to Lauto, Antonio, and Poppas, Dix P.; discloses a composition for tissue welding. The composition comprises an active compound, a solvent, and an energy converter and is insoluble in physiological fluids. A method for welding a tissue is also provided. The method comprises contacting a tissue with the above composition and exciting the composition such that the tissue becomes welded.
U.S. Pat. No. 7,186,659 titled “Plasma etching method”; to Fujimoto, Kotaro and Shimada, Takeshi; discloses an etching method for etching semiconductor devices, involves introducing etching gas in etching chamber, and exciting etching gas to plasma state to etch the material.
U.S. Pat. No. 6,197,026; titled “Electrosurgical instrument”; to Farin, Gunter and Grund, Karl Ernst; discloses an electrosurgical instrument for plasma coagulation of biological tissue e.g. for treating blood clots, haemostasis, thermal devitalization or destruction of pathological tissue.
US application 20080119843; titled “Compact electrosurgery apparatuses”; to Morris, Marcia; discloses a compact electrosurgical apparatus for use in electrosurgery such as flexible endoscopy.
U.S. Pat. No. 6,890,332; titled “Electrical discharge devices and techniques for medical procedures”; to Truckai, Csaba and Shadduck; discloses a medical instrument coupled to a source for introducing a gas to controllably form and capture transient gas volumes in a microchannel structure at the working surface of the instrument that interfaces with a targeted tissue site. Each of the microchannel features of the working surface carries an electrode element coupled to the electrical source. The energy may be applied to the targeted site in either of two modes of operation, depending in part on voltage and repetition rate of energy delivery. In one mode of energy application, electrical potential is selected to cause an intense electrical arc across the transient ionized gas volumes to cause an energy-tissue interaction characterized by tissue vaporization. In another preferred mode of energy delivery, the system applies selected levels of energy to the targeted site by means of energetic plasma at the instrument working surface to cause molecular volatilization of surface macromolecules thus resulting in material removal. Both modes of operation limit collateral thermal damage to tissue volumes adjacent to the targeted site.
U.S. Pat. No. 5,083,004; titled “Spectroscopic plasma torch for microwave induced plasmas”; to Wells, Gregory and Bolton, Barbara; discloses spectroscopic plasma torch suitable for use at atmospheric pressure.